In a large skillet, heat oil. Add chicken. Cook 5 minutes or until no longer pink, stirring frequently. Add water and pasta. Bring to a boil. Cover, reduce heat, and simmer 10 minutes or until pasta is cooked to desired doneness. Add vegetables, tomatoes, chiles, salt, pepper, and jalapeños (if using). Cover and cook 7 more minutes or until vegetables are cooked. Remove from heat. Sprinkle cheese on top. Cover and let stand 5 minutes or until cheese is melted*.